BROCKTON – Plymouth County District Attorney Timothy Cruz says he has requested expedited state testing of 400 grams of heroin seized in a Brockton drug bust Friday to rule out any link to the powerful prescription drug fentanyl.

Cruz’s request comes after the recent surge in heroin overdoses and suspected heroin overdose deaths locally. Brockton has seen six people die of suspected heroin overdoses in just two weeks.

“They will obviously test it. There’s a huge backlog. The turnaround time for drug (testing) is much longer than it was,” Cruz said Sunday.

In Plymouth County, there have been no confirmed overdose deaths involving fentanyl, Cruz said.

“I haven’t heard or seen any cases in our county with it,” Cruz said.

But authorities say they’ve been on the lookout for fentanyl, a powerful painkiller that has been implicated in dozens of fatalities in the Northeast, in some cases in combination with heroin. Authorities are also working to get heroin off the street.

Acting on a tip, authorities arrested an alleged heroin dealer in Brockton Friday and took 400 grams of heroin, with an estimated street value of about $30,000, and three guns off city streets, said Cruz, who called the arrest a “very successful operation and collaboration” with several law enforcement agencies.

“That’s one guy, now we’ve got to go on to the next one,” Cruz said of apprehending alleged drug dealers in local neighborhoods.

Police on Friday charged Cody Goncalves, 21, of 12 Addison Ave., with drug trafficking, possessing a loaded firearm and ammunition and drug trafficking within a school zone. He was scheduled to be arraigned today in Brockton District Court.

If convicted of trafficking heroin, Goncalves faces a minimum mandatory sentence of 10 years in prison.

Officers from local, state and federal agencies worked together to arrest Goncalves after Middleboro police on Friday received information about heroin trafficking at 12 Addison Ave. on Brockton’s East Side. Police learned that a large-scale heroin transaction was to take place in Brockton on Friday, authorities said.

Within hours, police set up surveillance outside the home of Goncalves, who fled on foot when he saw police officers in the area.

Officers chased after and eventually arrested Goncalves about 4:45 p.m. Friday. Police found approximately 150 grams of heroin, 3.5 grams of cocaine and $332 in his pants pocket, authorities said.

The search yielded an additional 250 grams of heroin, three loaded firearms and ammunition, about $40,000 in cash, packaging materials, scales, a money counter and other evidence from Goncalves’ bedroom, authorities said.

Mayor Bill Carpenter said Goncalves’ arrest resulted in a “major quantity of heroin taken off the streets of our city.”

Page 2 of 2 - “This bust is a major interruption in the flow of heroin into the streets of Brockton,” Carpenter said Sunday. “This was shared intelligence on a specific target. You had multiple agencies involved.”

Police Chief Robert Hayden said the arrest resulted from officers working closely to share information with other law enforcement agencies.

“We’re focused on what we’re trying to do,” Hayden said Sunday.

He spoke as the state is grappling with what officials call an epidemic of heroin overdoses, including in southeastern Massachusetts.

At least 185 people have died of heroin overdoses in Massachusetts during the last four months, state police said. Those numbers do not include fatal overdoses in the state’s three largest cities – Boston, Springfield and Worcester – because local police handle their own death investigations in those cities and state police do not track those cases.